66 DISEASES OF THE PLEURA 



Symptoms.— Hydrothorax develops rapidly and on both 

 sides of the thoracic cavity. Dyspnea results from compres- 

 sion of the lungs. In severe cases this compression may be 

 sufficient to cause edema of the lungs. The temperature is 

 normal. The shape of the chest is unchanged except when a 

 very large quantity of fluid is present causing the lower part 

 of the thorax to be depressed. 



Auscultation reveals hard respiratory sounds due to 

 increased respiration. Percussion over the lower part of the 

 chest reveals dulness, the upper level of which changes with 

 the position of the animal. Above this level tympany is 

 pronounced. 



Diagnosis.— Dyspnea with sudden onset in the absence of 

 other symptoms; percussion, and exploratory puncture. 



Prognosis.— Depends upon the causative disease. 



Treatment.— Medical.— Saline purgatives (magnesium sul- 

 phate, 8.0-12.0) may assist in the removal of the fluid by 

 eliminating fluid from the circulation. 



Surgical.— Thoracentesis (see pleuritis), when respiration 

 becomes distressed, and cyanosis is evident. Repeat as 

 often as necessary, using a new site for puncture each time. 

 Further treatment is to be directed to the primary cause. 



PNEUMOTHORAX. 



Definition.— Air in the pleural sac. 



Etiology.— Mechanical.— Perforating wounds from the 

 exterior (injuries, exploratory puncture, etc.); perforation 

 through the diaphragm by abscesses of the liver, stomach 

 or esophagus; perforation from the lung by abscesses or rup- 

 ture of air vessels in the normal lung. Gas-producing organ- 

 isms (B. aerogenes capsulatus) in the pleural exudates are 

 occasional causes. 



Pathology.— Pneumothorax rarely occurs by itself, usually 

 being associated with serofibrinous (hydropneumothorax) 

 or infectious pleuritis (pyopneumothorax), due to infection 

 being carried in with the air. A serous or purulent fluid is 

 found in the pleural sacs and the membranes are inflamed. 



